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Surface finish for sealing surfaces

I’m having some aluminum and stainless steel parts being made, and I’m curious if anyone knows what surface finish to spec for the sealing surfaces.

For full ocean depth products, it’s usually 32RA microinches. However, I only need my parts to be rated for 400m. I’m thinking something a little less refined, like 63RA, is the way to go.

Hopefully, if one of you BlueRobotics guys see this, you can kindly tell me what you guys spec for the flanges on your aluminum 400m pressure tubes;)


The Parker O-Ring Handbook has a bit of info, but I don’t think you’ll find anything coarser than 32 recommended for the sealing surfaces (63 for the two non-sealing surfaces in the groove). From personal experience, you’ll probably get away with 63, but in my opinion it’s one of those things where if you’re going to call it out at all, you might as well go with the recommended 32.

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Thanks for the feedback, @skcolb! Yes, I think you’re right; it definitely makes sense to spec 32.